Cash Flow Validation SOP

A cash flow validation SOP checks that you know, week by week, how much money will be in the bank, and it takes a day to build plus four weeks of checking against reality. You forecast every payment in and out by the date it lands, compare it with the bank each Friday and fix the forecast until it stays close. Startups with paying customers still die when the money arrives 60 days after the salaries leave. You finish with a trusted runway figure, the date of your lowest cash point and a clear moment to raise or cut.

What is the cash flow validation SOP and when should you use it?

A cash flow forecast tracks cash timing: when money lands in and leaves your bank account. A profit and loss forecast tracks when you earn revenue and incur costs, which can be weeks or months apart from the cash. This SOP uses the direct method, listing actual receipts and payments, and the 13-week cash flow forecast, a format used widely in corporate treasury and turnaround work because a quarter is long enough to see trouble coming and short enough to forecast precisely.

Neighbouring SOPs handle other questions. The break-even analysis SOP tells you the sales volume that covers costs. Financial scenario planning builds best and worst cases over years. This SOP tests near-term cash, where mistakes are fatal fastest.

Use it:

• When runway is under 12 months, or you don't know the number.
• When customers pay on invoice terms (30, 60 or 90 days) or through marketplaces with delayed payouts.
• Before buying stock, signing a lease or hiring, since each one moves cash before revenue.
• Before a fundraise, to know how much time you really have.

What do you need before you start?

• Bank exports for the last three months and today's balance in every account.
• A list of open invoices with due dates, and the payment terms in each customer contract.
• Every recurring payment: salaries and payroll taxes, rent, software, loan repayments, insurance (watch the annual ones).
• Tax dates: VAT or sales tax, payroll tax and corporate tax due dates for your country.
• Your payment processor's payout schedule, which decides when card payments become usable cash.

How do you run it, step by step?

1. Start from today's real balance

Use the bank balance on Monday morning, across all accounts, as week 1's opening cash. Never start from the balance sheet or the financial model; the bank is the only truth.

2. Forecast receipts by the date they land

For each expected payment in, use the date the money arrives: invoice date plus payment terms plus the customer's real delay, payout schedules for card sales, and grant or loan tranches only once signed. Revenue earned this month and cash received this month are different numbers.

3. Forecast payments by the date they leave

List every outgoing payment by due date: payroll, rent, suppliers, software, tax payments, loan repayments and the once-a-year bills founders forget, like insurance and annual software plans. Include VAT you collected from customers; it leaves on the tax date.

4. Find the lowest cash point and runway

Roll the 13 weeks forward and mark the week with the lowest closing balance. Calculate runway as cash divided by average monthly net burn over the last three months. Then check Paul Graham's question from his essay Default Alive or Default Dead?: at your current growth and costs, will revenue cover costs before the money runs out?

5. Compare with the bank every week

Every Friday, enter the real closing balance next to the forecast and explain any gap over 10%. Typical causes: a client paid late, a payment you forgot, a payout held by the processor. Update the assumption that caused it, roll the forecast forward one week, and keep the old version for comparison.

6. Fix the gaps you can control

Ask new clients for deposits or upfront payment, offer a discount for annual prepayment, invoice on signing instead of on delivery, chase overdue invoices on day one and move annual subscriptions to monthly. Negotiate longer terms with suppliers before you need them.

7. Set the funding trigger

Fundraising takes months, so this SOP sets a rule: start raising when runway reaches 6 months or more, never less. Write down the trigger date, the cuts you'd make if the raise slips, and the date you'd make them.

Template you can copy

Summary: lowest closing cash and its week, average monthly net burn, runway in months, fundraising trigger date.

Worked example: a corporate wellness workshop company

This is an illustrative case. A three-person startup runs wellbeing workshops for companies. The financial model shows a profit from month 8, and the founders believe they have €140,000 and about 8 months of runway.

The 13-week forecast tells a harsher story. Their three largest clients pay 60 days after an invoice sent after each workshop, so €46,000 of earned revenue arrives in weeks 11 to 13. A quarterly VAT payment of €22,000 leaves in week 6, and an annual insurance bill of €6,000 in week 4. The lowest cash point lands in week 9 at €44,000, about two months of costs, while the model had shown more than €100,000 at that date.

Four weeks of Friday checks show the forecast off by 14% in week 2 (one client paid 12 days late) and within 6% after that. Average net burn turns out to be €21,000 a month, so true runway is 6.7 months, well short of the 8 they assumed.

They change three things: a 30% deposit when a client books, invoices sent at booking, and monthly billing for their software plans. The lowest cash point rises to €78,000. Runway sits just above the 6-month trigger, so they start fundraising conversations the same month and apply for a regional startup grant in parallel.

What should you measure, and when do you stop?

The validation phase ends when the forecast hits the 10% target four weeks in a row. The weekly update itself never stops: it takes 30 minutes on Friday and becomes the most useful number in your company.

Which mistakes should you avoid?

• Forecasting from the profit and loss. Revenue earned and cash received happen on different dates.
• Counting money before it's signed. Grants, investment and big deals go in only when signed, and on the payment date.
• Forgetting VAT is not yours. Collected sales tax leaves on the tax date; spending it creates a hole.
• Missing annual bills. Insurance, domain renewals and annual software plans hit in one week.
• Starting the raise too late. With 3 months of runway you negotiate from weakness.

How can AI speed this up?

Export three months of bank transactions and ask an AI assistant to group them into the template's lines, flag recurring payments and list annual bills it can spot. Ask it to draft polite deposit terms and overdue-invoice reminders.

The human check: AI can't know when a client will really pay or which deal will close, so receipts timing stays your call. Check every category it assigns against the bank statement. Grants can stretch runway without giving up equity; the F/MS guide to EU grants for startups lists the main programmes, and Grant Grants covers startup grant calls in more depth.

Where does this SOP fit in your validation plan?

This SOP turns the plan into weekly cash reality within the Financial Validation SOPs:

1. Before it: real costs from cost structure validation and the volume you need from the break-even analysis SOP.
2. Alongside it: keep the long-range financial model consistent with the 13-week view.
3. After it: plan the raise with the fundraising validation SOP, and test bad cases with financial scenario planning.

FAQ

What is a 13-week cash flow forecast?

A week-by-week table of cash in, cash out and closing balance for the next quarter, built from real payment dates. It is short enough to forecast precisely and long enough to see a cash gap coming.

How do I calculate my startup's runway?

Divide your current cash by average monthly net burn (cash out minus cash in) over the last three months. Check the lowest point in your 13-week forecast too, since timing gaps can hit before the average says.

How much runway should a startup have?

This SOP treats 12 months as comfortable and 6 months as the latest moment to start raising, because fundraising takes several months.

What is the difference between cash flow and profit?

Profit counts revenue when earned and costs when incurred. Cash flow counts money when it moves. A profitable company can still run out of cash when customers pay late.